Featured app from Chapter 6 of "iPhone in Practice" by Bear Cahill published by Manning Publishing.
TimeDown is a very basic timer app that explores aspects of iOS development including the accelerometer.
"iPhone in Practice" takes the user step-by-step through creating this app including: the Settings Bundle, playing mp3 files, timer based functionality, shaking detection and more.
Learn more at: http://brainwashinc.wordpress.com/iphone-dev-book/
or
http://www.manning.com/cahill